Lake Delhi Dam ReconstructionDesign Alternatives Report

Lake Delhi Combined Recreational Facilityand Water Quality District

Transportation, Infrastructure, and Capitals Appropriations Subcommittee Presentation

February 2, 2012

I. Introduction

II. Project Objectives

III. Facility Description

IV. Field Investigation and Data Collection

V. Engineering Analysis

VI. Hazard Classification

VII. Repair Alternatives Development and Evaluation

VIII. Recommended Project

IX. Construction Schedule/Phasing

X. Construction Cost Estimate

XI. Moving Forward

XII. Questions

Alternatives Report Presentation Agenda:

Project Team

• Stanley Consultants• Gibbs Engineering and Surveying• Braun INTERTEC• Louis Berger Group• Lake Delhi Combined Recreational

Facility and Water Quality District

I. Introduction

• Document Condition of Lake Delhi Dam• Collect Data to Perform Technical Analysis and

Design of Dam Repairs• Review Regulatory Requirements• Complete Archaeological Reconnaissance • Develop and Evaluate Alternatives for Repairing

Lake Delhi Dam• Provide “Recommended Project”, Bringing Dam Into

Compliance with Current Dam Safety Standards.• Provide Estimate of Construction Costs and

Schedule.

II. Project Objectives

III. Description of Existing Facility Features

• Pool Area• North Embankment• North Abutment Wall• Powerhouse• Gated Spillway• Stilling Basin• South Buttress Wall• South Embankment

• Document Review• Topographic Survey• Property Research• Geotechnical Investigations• Structural Investigations• Electrical Investigations• Mechanical Investigations• Archeological Reconnaissance• Permitting Requirements Review

IV. Field Investigation and Data Collection

Document Review

• Original Design Drawings• Repair Drawings/Specifications• 1997 Ashton-Barnes Inspection, Stability, and

Spillway Adequacy Report• 2002 J.F. Brennan Co. Underwater Inspection

Report and Videos• 2004 DNR Inspection Report• 2008 J.F. Brennan Co. Underwater Inspection

Report and Videos• 2009 DNR Inspection Report• 2010 Stanley Consultants Inspection Report

Topographic Survey & Property Research• Topographic Survey

– Complete survey of Project Area – Gibbs– Supplement With Light Detection and Ranging (LiDar)

• Property Research – Gibbs – Review Gibb’s Previous Surveys– Review Gibb’s Previous Computer Drawings– Generate Property Line Exhibit Compiling Previous Work– Conduct Research at County Courthouse– Add In Geometry of Missing Plats– Obtained Coordinates of accessible property pins– Compare Surveyed Property Pins to Property line exhibit

and adjust

• Future Property Work

Geotechnical Investigations

• Field Investigations–Dam Site–Potential Borrow Evaluation–Laboratory Testing

• Geotechnical Parameter Development

Structural Investigations

• Initial Field Investigations–Concrete Condition Survey–Concrete Cores

• Review 1997 Ashton-Barnes Structural Stability Analyses

• Supplemental Investigations–Powerhouse/Spillway Foundation

Coring

Electrical Investigations

• Power Distribution

• Trash Rakes and Hydroelectric

• Equipment

• Lift Gates

• Emergency Generator System

Mechanical Investigations

• Lift Gates

• Wicket Gates

• Trash Rake

Archeological Reconnaissance

• Louis Berger Group, Inc. (LBG)• Reconnaissance Level Survey• Reconnaissance included Lake Delhi Dam and all Exposed

land areas within the former impoundment area• Records review to identify high potential areas• Field survey to investigate High potential areas• Seven New Sites Within Study Area• Total of 12 archaeological sites reported for the study area • No burial sites were identified within the study area• None of 12 sites has been evaluated for National Register• Additional site investigations recommended at all 12• Additional reconnaissance survey recommended for

selected portions of the study area

Permitting Requirements Review

• U.S. Army Corps of Engineers - Section 404 Nationwide Permit (NWP)

• Iowa DNR – Section 401 Water Quality Certification

• Iowa DNR – Sovereign Lands Construction Permit

• Iowa DNR – Floodplain Development Permit• Cultural Resources• U. S. Fish and Wildlife Service (FWS)

V. Engineering Analysis

• Geotechnical• Structural• Hydrology/Hydraulics• Hazard Classification

Geotechnical Analyses• Slope Stability• Seepage• Bearing Capacity• Settlement• Rock Anchor Capacity• Erosion/Scour Protection

Structural Analyses

• Structural Stability Analyses• Preliminary Structure Stabilization

Design

• Preliminary Concrete Structure Design– Service and Auxiliary Spillways– Training/Retaining Walls– Concrete Repair

Hydrology/Hydraulics• Lake Delhi Dam did not have sufficient hydraulic capacity

to meet current Iowa dam safety criteria.• Characterize Maquoketa River Flows at Dam.• Developing a hydrologic model of Delhi Dam watershed.• Developing a hydraulic model of Maquoketa River

upstream and downstream of Lake Delhi Dam.• Performing hazard classification and design flood analysis• Developing Lake Delhi Dam spillway concepts.• Addressing other hydraulic issues.

– Minimum Flow– Cofferdam By-Pass– Lake Draw-Down

Pool Impacts of Dam

VI. Hazard Classification

• Low/Moderate/High• Impacts Spillway Capacity/Cost of New Project• A detailed hazard classification analysis was

completed and results indicate that a reconstructed Lake Delhi Dam most closely matches the DNR’s Moderate Hazard Classification.

• Reviewed by Iowa DNR• Included in Dam Construction Permit Application

VII. Repair Alternatives Development and Evaluation

• Alternative Development/Evaluation Process

• Project Features With Multiple Alternatives

• Project Features Without Alternatives

Alternative Development/Evaluation Process

• “Brain Storming” session. • Establish District Objectives. • Review parameters for design

development and alternative evaluation.• Initiate the creative “brain storming”

process for alternative development.

• District Objectives • Meet requirements of current dam safety and design standards.• Minimize operation/maintenance requirements.• Maintain or improve upstream and downstream flow conditions.• Provide adequate (50+ year) service life.• Increase public safety at dam site.• Improve public recreational opportunities.• Reduce potential for damage from debris flow.• Provide cost-effective solution.• Constructability.• Minimize right-of-way impacts.• Minimize permitting requirements.• Provide opportunity for greater pool control.• Enhance fisheries opportunities.• Improve water quality.

Alternative Development/Evaluation Process (Cont’d)

Alternative Development/Evaluation Process (Cont’d)

• Brain-Storm Potential Reconstruction Alternatives

• Review brain-stormed alternatives in terms of Project Objectives and Feasibility of Construction

• Select Alternatives for Continued Development• Complete Conceptual Design of Selected

Alternatives

Project Features With One or More Feasible Alternatives

• North Embankment• Double Sheet Pile Wall• Cellular Sheet Pile Structure• Reinforced Concrete Walls *

• North Downstream Abutment Wall• Leave the existing wall as-is• Remove and replace the masonry block portion of the wall

with large block or mechanically stabilized earth (MSE) wall *

• Remove and replace the masonry block portion of the wall with a reinforced concrete wall

Project Features With One or More Feasible Alternatives (Cont’d)

• Powerhouse/Spillway Stabilization• FERC Stability Requirements• U.S. Army Corps of Engineers Stability Requirements *

• Powerhouse Bridge Deck• Epoxy Seal• Waterproof Membrane *

• Spillway Gate Repair/Replacement• Radial Gates• Crest Gates• Lift Gates *

Project Features With One or More Feasible Alternatives (Cont’d)

• New Spillway• Fuse Plug• Add Additional Lift or Radial Gates• Conduit Spillway Through Embankment• Labyrinth Weir

• Dual Level• Single Level *

• Pneumatic Crest Gates

• Minimum Flow Passage• Refurbish Wicket Gates• Install Valves in New Lift Gates *

Project Features With One or More Feasible Alternatives (Cont’d)

• New South Spillway Embankment Construction• Homogeneous Earth• Zoned *• Roller Compacted Concrete (RCC)

• Existing South Embankment• Remove and Replace• Improve Existing and Bench Into New *

Option Features

• Fish Passage• Recommendation – Not Practical

• Cost• Maintenance• Property Impacts• Length• Invasive Species• Dam Safety

Option Features (Cont’d)

• Recreational Amenities• Handicapped Accessible Fishing Pier.• Canoe Portage Trail.• Boat Ramp.• Observation Deck.

• Sediment Control and Removal• Dredging During Construction• Sediment Control Features

Non-Alternative/Option Project Features

• Site Access• Utilities• Powerhouse/Spillway Concrete Repair• South Buttress Wall Modification/Repair• Electrical and Controls• Safety Features• Archeological Mitigation• Property/Easement Acquisition

VII. Recommended Project

• Based on the project objective evaluation and cost comparison, reconstruction alternatives were selected for incorporation into the “recommended project.”

• “Recommended Alternatives” were combined with Non-Alternative Features for “Recommended Project”

IX. Construction Schedule/Phasing

• Goal – Pool in 2013• Recommend Two Phase Construction• Preliminary scheduling - construction could be accomplished

in one construction season• Assumptions

• Experienced contractor with sufficient resources• Normal weather• Normal river flows• Normal permitting timeline• 6 day work week

Phase I

Phase II

X. Construction Cost Estimate

• Combine Costs Estimates for Recommended Alternatives• Non-Alternative Item Cost Estimates• Design and Engineering During Construction Costs• Unit Costs Based on Published Values and Stanley Data

Base• Apply Mark-Ups

• Undeveloped Design Costs• Construction Contingencies• Escalation for Inflation

• Recommended Project:Approximately $11.9 million

XI. Moving Forward

• Present Alternative Report to Agencies• Initiate Detailed Design and Preparation of

Contract Documents • Permitting and Agency Coordination • Property/Easement Acquisition• Identify Qualified Contractors• Bid Project• Construction

XII. Questions ?